The present invention relates to pressurized containers, and more specifically, to airbag cushion inflators and to apparatuses and methods for manufacturing the same.
It is known to provide an inflatable restraint system including an inflator and inflatable airbag cushion for protecting the occupants of a transportation vehicle during collisions. Automotive vehicles, for example, can be supplied with driver side airbag modules, passenger side airbag modules, and side airbag modules. Such airbag assemblies, for example, may be located within the hub of the steering wheel and in a recess in the instrument panel for protection of the vehicle occupants seated in opposing relation to such assemblies. In other examples, such airbag assemblies may be located within the seats and/or door panels for protection of the occupants during a side-impact event.
Methods for manufacturing airbag inflators typically require the welding of a number of parts together, particularly in light of the increasing complexity of inflators. Prior welding techniques used to manufacture airbag inflators have been either laser welding or friction welding.
Laser welding is a welding technique used to join multiple pieces of metal through the use of a laser. The beam provides a concentrated heat source, allowing for narrow, deep welds and high welding rates. The process is frequently used in high volume applications, such as in the automotive industry. Some of the shortcomings of laser welding are the very high cost of equipment and consumables such as shielding gas and lenses, high cycle time, uncertainty of consistently making a leak-tight joint, and somewhat low weld strength with a potential for porosity (due to high cooling rates, cracking can be a concern, especially when welding high-carbon steels).
Friction welding is a technique used to weld thermoplastics or metals by the heat generated through mechanical friction by rubbing the members to be joined against each other under pressure, with the addition of an upsetting force to plastically displace material. Some of the shortcomings of friction welding are the high cost of equipment, weld flash on both sides of the weld joint (some of which may be loose and difficult to remove), difficulty in controlling the finished part length upon welding, high cycle time, and the difficulty of gripping thin plates using a friction welding apparatus.
Accordingly, it is desirable to provide for the manufacturing of airbag inflators using welding techniques that can overcome at least some of the shortcomings of the prior welding techniques.